Negative regulation of Wnt signaling mediated by CK1-phosphorylated Dishevelled via Ror2

Area of Science:

• Cell Biology
• Molecular Biology
• Signal Transduction

Background:

• Dishevelled (Dvl) is a key mediator in Wnt signaling pathways.
• Wnt3a and Wnt5a activate casein kinase-1 (CK1) to phosphorylate Dvl, forming phosphorylated and shifted Dvl (ps-Dvl).
• The precise function of Dvl phosphorylation remains largely unknown.

Purpose of the Study:

• To investigate the functional role of ps-Dvl.
• To elucidate the interaction between ps-Dvl and Ror2, an alternative Wnt receptor.
• To understand how this interaction impacts canonical and noncanonical Wnt signaling.

Main Methods:

• Cell-based assays to detect protein-protein interactions.
• Western blotting to visualize Dvl phosphorylation (ps-Dvl).
• Analysis of Wnt signaling pathway activity in mammalian cells and Xenopus explants.

Main Results:

• Ps-Dvl directly interacts with the C-terminal domain of Ror2 at the cell membrane following Wnt3a or Wnt5a stimulation, dependent on CK1 activity.
• The Dvl C-terminus, exposed in ps-Dvl, binds Ror2 and functions as a negative regulator of canonical Wnt/beta-catenin signaling.
• Both the Dvl C-terminus and CK1epsilon inhibit the Wnt5a/Ror2/ATF2 pathway.

Conclusions:

• Dvl phosphorylation by CK1, leading to ps-Dvl formation, is crucial for its interaction with Ror2.
• The ps-Dvl-Ror2 complex mediates negative feedback on canonical Wnt signaling via the Dvl C-terminus.
• This mechanism suggests a Ror2-dependent negative feedback loop regulating diverse Wnt signaling branches.